Gas manifold

A gas manifold installable in a combustion apparatus to distribute fuel gas to a plurality of burners for burning the fuel gas included in the combustion apparatus, the plurality of burners being grouped into a plurality of burner sets, the combustion apparatus performing stepwise switching of the number of burners to burn the fuel gas by causing each of the plurality of burner sets to burn the fuel gas, the gas manifold comprising:

• a main channel configured to allow passage of the fuel gas fed from outside;
• a plurality of distribution chambers each located for a corresponding burner set of the plurality of burner sets, the plurality of distribution chambers being configured to receive, from the main channel, the fuel gas to be fed to the plurality of burners in the plurality of burner sets;
• a plurality of nozzles each located for a corresponding burner of the plurality of burners, the plurality of nozzles being configured to feed the plurality of burners with the fuel gas flowing into the plurality of distribution chambers;
• a plurality of distribution channels branching from the main channel and connecting the main channel to the plurality of distribution chambers;
• and
• a plurality of on-off valves each located at a corresponding distribution channel of the plurality of distribution channels to open or close the corresponding distribution channel,
• wherein the plurality of distribution chambers include a maximum distribution chamber and distribution chambers other than the maximum distribution chamber, and the maximum distribution chamber includes more burners in the corresponding burner set than each of the other distribution chambers,
• the main channel includes a flow guide configured to guide the fuel gas toward a maximum distribution channel being a distribution channel included in the plurality of distribution channels connected to the maximum distribution chamber, and
• the flow guide comprises a projection structure that makes a narrow passage in the main channel, a sectional area of the narrow passage being constant and narrower than that of an upstream passage and a downstream passage thereof.